4-aminobiphenyl is being fed to a group of beagles for the purpose of inducing bladder cancer. These animals and matched controls are being observed clinically (weight, appetite, cystoscopy) and their serum proteins, leukocytes and immunologic reactions in vivo and in vitro are being compared. Thus far (6 months after initiation of carcinogenic treatment) no major deviations have been noted but carcinogenesis with 4-aminobiphenyl requires a period of 12-18 months. Studies are being continued and will include assessment of humoral and cellular parameters of immunity utilizing cellular antigens including tumor antigens, mitogens, protein conjugates of the carcinogen and bacteria and viruses used in the immunization of animals. When tumors develop surgery will be performed on one-half of the animals and their immunologic status will be compared with that of animals with growing tumors and controls.